1. Field of the Invention
The present invention relates to a composite assembly for a motor vehicle.
2. Description of the Background Art
It is increasingly customary for technical design reasons to mount electroacoustic transducers (in the following called, for example, a distance sensor concealed behind a part of the motor vehicle (for example, a bumper cover).
This has in fact the advantage that the design of a motor vehicle in the area of the mounted distance sensors is not negatively affected by these otherwise visible distance sensors, but it also entails certain functional disadvantages.
It is problematic that the distance sensor in the case of concealed mounting must send and receive ultrasonic waves through a wall element of a motor vehicle, which reduces the efficiency of the dispersion of ultrasonic waves, on the one hand, and the sensitivity of the distance sensor, on the other.
In this regard, the emission behavior of concealed mounted distance sensors can be divided into two cases in principle:
On the one hand, a “direct” acoustic emission occurs perpendicular to the surface of the wall element, and, on the other, an “indirect” acoustic emission occurs approximately at a 45 degree angle, which is caused by the surface waves generated on the wall element.
Overall, this results in emission characteristics in which a clear drop in the sound pressure level is noted in a radiation angle range of about ±22 degrees.
This, “partial blind range” has the result that during the application of distance sensors it must always be assured that this indicated blind range is covered by an adjacent distance sensor.
DE 10 2006 034 997 A1, which corresponds to U.S. Pat. No. 7,518,491, discloses a composite assembly for a motor vehicle. In this regard, an intermediate element is employed, which can be formed plate-shaped and rectangular in outline. Furthermore, it is also proposed to form the intermediate element as a truncated cone. The intermediate element is said to have a favorable effect on the directivity of the electroacoustic transducer and its sensitivity.